Today commercial household vacuum cleaners resemble in function and handling basically the models from the beginning of the twentieth century, even if improvements to the suction power, noise emission and air-filters have been achieved during the years. The various models available on the market differ apart from their design mainly in the power of their engines, which in some cases can be controlled electronically, the noise damping and the quality of their filters.
The classical floor vacuum cleaner consists of an engine block on wheels connected with a tube and various nozzles. For the suction of floor surfaces, usually a rigid nozzle mounted on a telescope handle, which renders possible to clean an area of about 20 cm width, is used. As an alternative, the engine block can be integrated in the telescope handle. For smooth floor surfaces, most models have a short brush, which can be pushed out of the nozzle by means of a switch operated by hand or foot. Additionally, with some models, a nozzle with an horizontally rotating brush can be used to enhance the cleaning effect. The drive of this brush is realised electrically or indirect by the air stream.
To enhance the cleaning effect, especially for the use with cleaning machines, an arrangement of several circular brushes, which by a planetary gear are put into multiple rotation, is described in the German patent application 1057154. Other known cleaning machines use two stationary circular brushes at the two front ends which the automatic vacuum cleaner in DE 43 07 125 A1 possesses to move dirt from the direct lateral area of the vacuum cleaner to a stationary suction nozzle.
In the German patent application DE-OS 21 01 659, a vacuum cleaner with a telescope suction arm with a circular profile is described, with a suction nozzle mounted at the end of the arm. The vacuum cleaner is not mobile, but can only turn within a certain angle by means of a rectangular positioned steering wheel. There are no sensors, only the lateral parts of the suction nozzle are seated rotatory by a spring to be able to avoid obstacles.
In the British patent application GE 20 38 615 A, a vacuum cleaner with remote control and a circular base on three wheels, two of which are driven wheels, is described. This vacuum cleaner has a stationary suction nozzle beneath the base. A method of steering the device or sensors are not contained in the patent application.
The patent application U.S. Pat. No. 5,095,577 describes a self moving vacuum cleaner, whose suction nozzle is mounted at the end of a suction tube which is rolled up on a cylinder and thus can be extended. The device is enabled by mechanical sensors and steering elements to follow the contour of a wall while extending the suction nozzle or rolling it up.
The same mechanism, but able to extend one or two suction nozzles rectangular to the moving direction of the device, is described in the patent application U.S. Pat. No. 5,199,996, though the vacuum cleaner is only moved in parallel courses respectively in courses rectangular to the prior courses.
A further method of controlling an automatic vacuum cleaner is contained in the patent application DE 43 40 771 A1. In this arrangement, the vacuum cleaner is guided along the inner contour of the surface to be cleaned, thus detecting the contours of the surface to be cleaned. Then, a micro processor compares the form of the surface to be cleaned with the previously stored contours to select the most appropriate cleaning program. For orientation, apart from optical and ultrasonic sensors on the surface of the vacuum cleaner, a magnetic field sensor is used to determine the direction.
In EP 01 42 594 B1 and DE 43 07 125 A1, a similar method of controlling is described, but with the additional capability of the vacuum cleaner to plan and perform independently parallel cleaning courses after one cycle to determine the contours of the surface to be cleaned, without the previous storing of a cleaning program for a certain room.
The patent application DE 196 14 916 A1 describes an automatically working moving robot, whose orientation is based mainly on the stereoscopic evaluation of the data of two video cameras. A concrete controlling method though is not described.
In the patent application EP-A-38 26 93, a method of controlling on the basis of a recursive algorithm is described for a suction robot, wherein the respective closer area around the suction robot is cleaned and the suction robot then by moving ahead and back, followed by a turn with a certain angle of turning, is moved to a new place until a given area is covered. To determine the respective new position, a systematic algorithm is utilised.
In the patent application U.S. Pat. No. 5,696,675, a moving robot with a lateral displaceable arm is described, which possesses a special construction with supporting wheels to support the suction arm and whose sensors are able to detect an obstacle for the arm and for the vacuum cleaner.
In the patent application U.S. Pat. No. 5,677,836, a device is described, comprising the transmission of the co-ordinates from one map to another map.
In addition to the deterministic controlling methods mentioned above, on the fair xe2x80x9cDOMOTECHNICA 99xe2x80x9d, a self working vacuum cleaner was presented, which according to the patent application EP 0 769 923 B1 mainly is controlled stochastically. Here, the vacuum cleaner moves in a certain direction until an obstacle, which is detected by sensors, blocks its way. The vacuum cleaner turns away from the obstacle and continues its way in another direction, until a new obstacle forces it to change its course, and so on.
Despite the improvements in certain fields during the years, vacuum cleaning remains a time consuming and exhausting housework . Today""s manual devices require frequent bending, sometimes the moving of objects as well as the strong rubbing of the suction nozzle. Apart from that, because of the inflexible suction nozzles, damage of delicate furniture may occur. When changing from smooth surfaces to carpet-covered surfaces, each time the suction nozzle has to be switched manually to achieve the best cleaning effect. If narrow places have to be vacuumed, a troublesome change of the suction nozzle is required.
The known methods of controlling autonomously working vacuum cleaners show the following disadvantages:
Methods of controlling, which require a manual route planning, are to complicated and very inflexible, because especially in a household, the floor surface which is to be cleaned changes continuously because of the moving of objects.
Methods of controlling, which before starting the actual vacuum cleaning process detect the border lines of the floor surface which is to be cleaned and determine their cleaning courses with this information, are overstrained, if many obstacles, e. g. furniture, force them to frequent evading movements. Apart from that, because of the detection of the border lines, it takes a comparatively long time until the actual suction process starts and the method only works in closed room areas. Moreover, it is not possible to define a certain starting point for the vacuum cleaner, from where the cleaning process is to be started.
Exclusively stochastic methods of controlling work unsatisfactorily as well, because certain areas are covered very often whereas other areas are covered rarely or not at all, so that a non-uniform cleaning effect is achieved. The cleaning process also lasts very long and there is no criterion of ending the process.
In the recursive method of controlling, described in the patent application EP-A-38 26 93, the vacuum cleaner has to cover very far distances because of the continuous moving ahead and moving back, which leads to long vacuuming times and to a non-uniform covering of the area. A starting point can be indeed determined, but the vacuum cleaner moves away from this point in a certain direction without completely cleaning the direct environment before.
The self moving vacuum cleaners controlled by the methods described above are not suitable to replace the manual vacuum cleaners because of the following reasons:
Powerful vacuum cleaners possess a bulky form and cannot be used in narrow spaces, also because the damage of delicate furniture cannot be excluded. Moreover, except from complicated driving methods, several and complicated sensors are used which render the devices susceptible and very expensive. To improve the accessibility, recently very low devices with a circular base have been developed. But this limits the possible size of the batteries and so the reach and the power of the vacuum cleaner. Also, many areas in corners and niches and along the edges of furniture cannot be cleaned, because they are not accessible for the vacuum cleaner. Vacuum cleaners relying on a wire based power supply, in principal because of the necessary connecting cable are not flexible enough to be able to clean efficiently housing spaces with numerous obstacles.
Thus, the invention is based on the task to provide a flexible cleaning system, which on the one hand is able to adapt to any kind of floor surface with any kind of obstacle, and on the other hand avoids unnecessary multiple cleanings of certain areas, while other areas are not sufficiently covered or are not covered at all. Apart from that, the cleaning process should he enabled to start at any point determined by the user without having to previously detect the contours of the room.
To provide a serious alternative to commercial vacuum cleaners, the device controlled by the method should cover every floor area as well as edges of furniture and narrow niches, while a high cleaning effect is necessary and damages have to be excluded. The device has to be big enough to contain a sufficient capacity of batteries. By the means of adequate insulation, most of the produced noise can be damped. Moreover, the vacuum cleaner should be constructed as simple as possible, be robust and dispense with complicated sensors to render possible a low cost production.
According to the method of automatic controlling a self-moving device, especially a vacuum cleaner, with range-respectively contact-sensors, a closer area around the device is individually determined and scanned, e.g. by a movable arm. The device is then moved to a respective new position until no position can be selected anymore. At this, the determination of the closer area and the selection of the position is realised mainly on the basis of the information of the surroundings, which is stored in a map (vacuuming field) and updated in each step, at this to determine the respective next position. An optimising of all positions, which have been stored and can be approached by the device, is performed by calculating and comparing for each of these positions certain evaluation parameters like distances or areas in the reach of a possible new position, which have not yet been scanned, and by selecting the position with the best evaluation result.
The scanning of the closer area is realised, starting with the retracted state of the arm, by repeated turns to the left and the right with an increased length of the arm at each turn, until a given maximum arm length is reached and the arm is then, following a last turn, retracted again.
The fully automatic method of controlling, especially of controlling a self moving vacuum cleaner, with range and contact sensors, which was developed to solve the described problems, shows the following features:
Around the device, a closer area is determined, which is scanned by sensors, and at the borders of this closer area, possible new positions for the device are stored. Then, after selection of a position stored in the current or previous step, dependent on the degree of accessibility, on an assigned priority and under consideration of the existence of not yet scanned areas in the range of a possible new position, the selected position is approached and then the described sequence of steps is repeated until a given area is completely covered or no new positions can be selected anymore.
The floor surface scanned by the sensors is stored in a two dimensional data field to mark herein by means of certain states obstacles detected during the scanning, free areas and possible new positions for the device. This data field, in which successively a copy of the accessible floor surface with the contours of each obstacle within and the limiting borders of the floor surface is generated, is used to determine the controlling parameters for the device and to control the already covered area.
Further advantageous possibilities of the method of controlling are as follows:
The closer area can be determined by the reach of the sensors, which are mounted on the device flexibly or stationary. At this, sensors can be used which are sensitive to direction and possess distant effect, or simple contact respectively range sensors, which are guided above the surface which is to be scanned by a suitable mechanical arrangement. But the scanning of the closer area can also be performed by emulating the effects of sensors with distant effect or of flexible sensors by moving the complete device, so that the device detects the maximum closer area within reach including potential obstacles with sensors without distance effect. In this case, any area relative to the position of the device can be defined as a closer area.
When using sensors which do not provide any information about the direction, after the detection of an obstacle its exact position is determined by consideration of the direction of detection.
To limit the number of stored positions, after the scanning of the closer area, new positions are only stored where no obstacles have been detected and where no areas border, which have been already scanned from a previous position of the device. This condition is realised most simply by storing only new positions at those borders of the closer area which are marked in the data field as not yet scanned.
While storing a point (x,y) into the data field with the dimensions x_max and y_max, for negative co-ordinates the transformation into a positive range of co-ordinates, e. g. by forming x_maxxe2x80x94|x| respectively y_maxxe2x80x94|y| is realised.
When scanning again an area already marked in the data field, the states of this area are updated according to the new sensor data. Thus it is realised, that because of the overlap of the scanning areas and especially if obstacles are located in an area already scanned, the stored information about the scanned area will always be updated.
When selecting a new position for the device, only such positions are taken into consideration, which are marked in the data field as not yet scanned. This criterion provides a simple but effective method to consider the not yet scanned areas in the range of a new position: If in the meantime a position is marked as already scanned since its storage in the data field, it can be deduced that the surrounding areas as well have been covered because of the usually compact closer areas. Because of that, such a position can be deleted, since it does not have to be approached anymore.
When storing new positions, different priorities for the positions can be assigned, e. g. dependent on their location and nearness in comparison with other positions. When selecting a new position for the device, only such positions are considered whose priorities are not inferior to that of a new position already preliminarily selected in the current step.
When selecting a new position, only such positions are considered, which are located within a certain partial area. This partial area will be modified during the process, if within the current partial area no new position can be selected. This method renders possible an indirect influence on the movement of the device, for instance to ensure that the device mainly covers coherent areas.
When selecting a new position, the distance and the direction from the current position can be used as a criterion of valuation.
Moreover, when selecting a new position for the device, by evaluating the data field it can guaranteed, that the new position can be reached by the device on a direct route, allowing only areas to be traversed which have already been scanned and which are not marked as an obstacle.
Furthermore, it is possible when selecting a new position to consider the covered distance since the storage of a possible new position, to limit the influence of backlash. This can for instance be realised by marking as free an additional safety distance at the borders of the area which is to be traversed, whose width depends on the covered distance, when checking the possible reach of a position in the data field.
After selecting a new position by evaluating the data field, the shortest route within the already scanned area under avoiding obstacles is determined and the device is moved along this route.
The device can be set back on any previous position and when setting back the device over several positions, certain positions in between can be skipped, if a checking of the data field shows that the device does not have to traverse areas marked as obstacle during its movement.
If an unexpected obstacle blocks the movement of the device, it will detect the contours of the obstacle by scanning it with the sensors. Since during the movement of the device usually no new scanning of the route occurs, because at this only areas are traversed, which are marked as free in the data field, the device can meet unknown obstacles caused by the movement of objects or maybe because of backlash. In this case, the movement of the device is interrupted, the closer area is scanned to update the stored data, and then a new position is selected.
After approaching the new position, the new closer area is determined by evaluating the data field, so that only a small overlap with already scanned neighbored areas occurs.
Especially advantageous for the use of the invention as a vacuum cleaner is the fact that during the scanning, at the same time the floor surface is cleaned.
To ensure this, the scanning can be realised by a movable arm, so that not yet scanned areas are always covered at first by the front end of the arm. When contacting an obstacle, the arm is guided along the detected obstacle at the smallest possible range. Especially advantageous can be the selecting of the closer area around the device in form of the sector of a circle, with the scanning being performed by repeated turns of the device to the left and the right with an increased length of the extensible arm at each turn. To avoid the repeated scanning of the same obstacle, the arm can be shortened in the range of those angles where an obstacle has already been detected.
By evaluating the information in the data field it is ensured that the cleaning of the floor surface is only conducted in areas which are marked as not yet cleaned in the data field.
A device suitable for the methods of the invention, which besides a suction unit can of course contain other cleaning units, e. g. for sweeping, cleaning by steam or by spray or which can be used alternatively for other purposes such as lawn mowing, search of objects or controlling purposes, shows the following substantial features, which can be combined:
The device with propelled wheels and steering wheels respectively propelling wheels which can be steered and sensors and an extensible arm is characterised by the fact that apart from two propelled wheels the lower front end of the arm (head) is used as a third support, which rests on rollers, balls, wheels or bristles.
The device with propelled wheels and steering wheels respectively propelling wheels which can be steered and sensors and an extensible arm with a head positioned at its front end is characterised by one or several rotating circular brushes positioned at the head.
The device with propelled wheels and steering wheels respectively propelling wheels which can be steered and sensors and an extensible arm is characterised by range or contact sensors at the arm to detect obstacles, which by moving the arm and turning the device can cover the closer area and detect obstacles for the movement of the arm as well as obstacles which only impede the movement of the device.
The device with propelled wheels and steering wheels respectively propelling wheels which can be steered and sensors is characterised by the fact that the drives are connected elastically with the respective wheel, e. g. by means of a worm drive, with the displacement of the drives caused by the blocking of the device by an obstacle being detected. This feature renders it possible to renounce on an additional outer contact sensor, which would have to surround the device completely and which would be mechanically complicated.
Additional advantageous features of the device are characterised as follows:
The drive of the circular brush(es) is realised via a movable shaft by a motor which is positioned at the base of the device.
Each brush is surrounded by a thick ring of soft bristles which are adjusted diagonally towards the outer part of the brush to remove dust from the edges of furniture and to avoid damage. Moreover, the brush can possess bristles which are adjusted diagonally towards the inner part of the brush and can solve dirt from the floor, support the device and in addition to that, are able to lift the head of the device at small steps e. g. at the edges of carpets.
If several circular brushes are used, the axes can be arranged and propelled so that the brushes move the dirt in the direction of the suction nozzle beneath the head. Especially advantageous is an already known arrangement as described in the German patent application 1057 154, in which the brushes are put into self rotation by means of a planetary gear while at the same time circulating under the head.
Special sensors at the head detect obstacles for the movement of the arm. A sensor for this purpose can advantageously be constructed in the form of two electrical conductors positioned within a short distance to each other around the head of the arm, of which the outer one is pressed elastically against the inner one when touching an obstacle, thus closing an electrical circuit.
Other sensors at the head detect obstacles for the movement of the device which do not block the arm. For this purpose, a range sensor can be used which measures the clear height above the head, using e.g. ultrasonic or electromagnetic waves. Additionally, a sensor, e. g. in form of a mechanical push button or contact-free, can detect steps in the floor surface beneath the head to avoid tipping of the device. The movable arm advantageously is constructed as a telescopic arm with a rectangular profile to provide, when used as a vacuum cleaner, a big sectional area for the air stream while constructed as low as possible.
If the device is not supported at the front end of the arm, it is advantageous to construct the telescopic arm so that at its rear end it is mounted rotating around a horizontal axis respectively vertically flexible to guarantee a good floor contact of the head. Also in this case, an additional support with an integrated ball to roll off can be positioned under the front end of the arm, which allows any lateral movement.
By shifting of weight, the resting pressure of the head can be varied.
After releasing of the blocking sensor, the device is advantageously placed back until no further blocking is detected by the sensor. Then follows a repeated advancement, though with reduced speed, to distinguish between real and fake obstacles. If the sensor releases the first time because of a real obstacle, it will release again at reduced speed. If the cause is only a step in the floor surface which can be overcome, e. g. the edge of a carpet, or an increased frictional resistance of the brush, the reduced speed causes a reduction of the dynamic forces and the frictional forces, thus preventing a new release.
By means of the example of a vacuum cleaner, the process of the method of the invention is explained in detail, while for better understanding, the construction of the device is described at first. The method of the invention can of course be applied independent of the device described in the following and also with any other suitable device.